Manufacture of magnetic materials.



UNITED STATES PATENT OFFICE.

ROBERT ABBOTT HADFlELl), OF SHEFFIELD, ENGLAND.

Application filed June 8.1905.

Specification of Letters Patent.

Patented April 23, 1907.

Serial 'No. 264,227.

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Be it known that I, ROBERT ABBOTT HA1)- FIELD, a subject of the King of Great Britl ain, and a resident of Shellield, county of York, England, have invented GOItitlIlllQW and useful Improvements in the Manufacture of Magnetic Blatcrials, of which the fol lowing is a spcci'hcation.

My invention relates to the manufacture of materials having magnetic properties, suitable for use in various electrical apparatus, such as ballast coils, transformer plates 3 and the like.

The ob ect of my invention is to secure a combined very low hysteresis and eddy current loss.

In former Letters Patent ot' the United States granted to me on December 1st, 1903, No. 745,829, and August 9th, 1904, No. 767,110, I have described the manufacture of material for the above indicated purpose by adding to iron certain proportions of silicon, aluminium or phosphorus, (either one or any two or all three of these elements) and I peculiar tions hereinbefore mentioned, namely silicon j and phosphorus, the silicon predominating very largely in relation to the phosphorus, as

the amount of phosphorus used is about eleven per cent. of the amount of silicon. carrying out further experiments for obtaining still better results, I have discovered that it is highly advantageous to increase the proportion of the addition used in conjunction with the silicon, and while silicon still IOI'IHS 1 the bulk of said addition, the percentage of the other ingredient relatively to silicon has been increased materially from the eleven per cent. previously disclosed. This will be e prop In the expresent lated, and in regard the percentage employed should be low if the best results are desired.

The important feature of the present invention is the relative proportion of silicon and aluminium. I may state, however, that instead of aluminium I may employ phosphorus as an equivalent, or aluminium and phosphorus may be used together instead of aluminium alone. \Yhere inthe claim I have referred to aluminium, it will be understood that these equivalents are also covered. It i will be seen that in Example A the proportion i of aluminium to silicon is about as 1 103.22 or l 31%. .In Example B the proportion of aluminium rises to 1 to l .5 or (56%.

, The manufacture oi the alloy consists i simply in taking pure iror a'id melting it in a l common crucible or electrically along with the additions named, that is silicon and aluminium (and phosphorus if such is cm- I ployed). Instead of employing the crucible process I may use the decarbonizcd or desilil conized iron produced by any steel making I process such as the open hearth, the pncu matic or the electrical process, adding to l such iron the desired percentage of silicon and aluminium. :into suitable ingots which, if desired, are forged or rolled into an appropriate shape. The silicon and aluminium or plmsphorus 1 maybe added during the process if made in crucibles or at the end.

, The material produced in accordance with my present invention so far as above described, is very valuable, since its total loss in service from hysteresis and eddy currents isyery low. The material is, therefore adnnrably adapted for use in transformers and other electrical apparatus.

1, As regards the varh tions which may be l allowable in practice in the percentage of silicon and aluminium employcd,l may say i that the percentage of silicon may vary from l about .20 percent. to about 5%, and the percentage of the other portion of the addition (that is, in the examples, aluminium) may vary from about .05 per cent. to about 3.75 per cent; but so that, the proportion of aluminium or its equivalent, relatively to sili con, will be from 25% to 75%, as l have pointed out hereinbe'fore. This is a. much higher proportion of the non-silicm'i addil ion than has been indicated in my earlier patents. Owing to the change of proportions, I have been able to secure a material improve- The molten alloy is poured IOO IIO

ment in the desirable electrical and magnetic qualities of the material. The hysteresis loss of the material referred to in E'xmnple. A only .37 Watts per pound for the east material, and only .17?- wzitts per pound for the same material rolled. her the alloy specified in Example 13, the hysteresis loss was .31 watts per pound for the cast matei rial end .21 watts per pound for the rolled material.

1 claim as my invention:

A low hysteresis magnetic material con taining iron With an addition of silicon and aluminium; said addition amounting. together to from one-fourth to eight per cent.

of the iron, and the proportion of aluminium I5 amounting to from twenty-live to seventy five per cent. of the silicon contents.v

Tn testimony whereof, I have hereunto set my hand in the presence of two subscribing witnesses.

ROBERT ABBOTT HADFIELD. W'itnesses:

LESLIE G. W HEELER, Ens/risen IT. BARKER. 

